Originally Posted by NuggetMrMan
Oh because I have two goldfish 2 small fish and 3 corys I think that's what they are called.
The tank is very overstocked. Goldfish are coldwater fish. Two fancy goldfish require an absolute minimum of 30 gals, 2 common goldfish require a minimum of something absurd like 120 gallons. Cories are tropical fish that require a heater. Pygmy cories such as hasbrosus can be kept in 10 gals and larger. Medium sized cories like julii and pandas should be kept in no smaller than 20 gals. Larger cories like emeralds (green) and albinos should be kept in no smaller than 29 gals. Cories are shoalers than should be in groups of 6, but no less than 4. Your other small fish are most likely schoolers that should be in a group of 6 or more, but it's hard to say based on that description. The ammonia (waste) your goldfish are producing will most likely lead to the demise of your fish. The tank is so terribly overstocked.
A 7 gallon tank would be approrpiate for 1 betta with a nerite snail and some shrimp. Or some nano fish such as mosquito rasbora, celestial pearl danios, and scarlet badis, to name a few and small inverts like a nerite snail and shrimp. Besides the betta, these may or may not be fish that easy to find in your local stores. They are not typically available in the chain stores. Of the common fish you see in places like Petco, Petsmart, and Walmart, only bettas are appropriate for a tank that size. And to clarify, they are tropical fish that need a heater.